1. Field of the Invention
The present invention relates to a humbucking pick-up assembly for stringed musical instruments and, more particularly, to a pick-up assembly for stringed musical instruments including a magnetized, signal coil and an unmagnetized, disassociated, humbucking coil.
2. Description of the Prior Art
The present invention relates broadly to electrical musical instruments of the stringed type. It is particularly applicable to an electrical guitar or similar musical instrument having a plurality of stretched strings extending across a body and a neck, between the head of the instrument and a bridge assembly connected to the body, in which the strings are caused to vibrate by plucking or picking same.
In order to derive an output from such an electrical guitar or other similar electrical musical instrument, the instrument is conventionally provided with an electromagnetic pick-up comprising a number of magnetic elements (pole pieces) having wound therearound a conductive coil. Typically, one such magnetic element is disposed directly beneath each string of the instrument. The strings are constructed of a magnetizable substance, such as steel, and, therefore, become part of the conductive path for the magnetic lines of flux of the pole pieces. Accordingly, when any of the strings are caused to vibrate, this causes a disturbance in the magnetic field of the associated pole piece. This has the effect of generating a voltage in the conductive coil, which voltage may be suitably amplified and transmitted to a loudspeaker system.
With such an electromagnetic pick-up construction, a number of problems exist. Electric guitars and other similar electrical musical instruments are used in areas having strong magnetic fields from lighting fixtures, motors, transformers, and the like, and these magnetic fields are sensed by the pick-up as an extraneous noise source. In the United States, such source typically has a frequency of 60 Hz, the usual power line frequency. These magnetic fields induce voltages in the coil which are also amplified and transmitted to the loudspeaker system, manifesting themselves in an objectionable hum.
In order to overcome this problem, it is known to provide a pick-up for an electrical musical instrument including a pair of identical pick-up assemblies, each having a plurality of magnetic pole pieces and a coil, the pick-up assemblies being positionable in parallel, spaced, closely adjacent relationship. All of the pole pieces of one of the pick-up assemblies have their north poles adjacent to the strings and their south poles relatively remote from the strings whereas all of the pole pieces of the other pick-up assembly have their south poles adjacent to the strings and their north poles relatively remote from the strings. The coils of the two pick-up assemblies are wound in opposite directions and the two coils are connected either in series or in parallel. Because the direction of current flow in each coil is governed by the magnetic polarity, the direction of current flow in one coil is opposite to that of the other coil for each string. However, since the directions of the windings of the two coils are opposite, the signal induced in each coil as a result of string vibrations is additive and the output signal is the sum of the signals induced in each coil.
On the other hand, signals picked up by the coils from power line sources produce currents in the coils which are independent of the magnetic polarity and, accordingly, such power line sources produce voltages that are in phase. However, since the coils are wound in opposite directions, these in phase signals cancel and the output signal is the difference between the power line signals induced in each coil. This means that any noise from power line sources, which is otherwise manifested as an objectionable hum, is effectively reduced or cancelled. It is for this reason that such an arrangement is typically characterized as a humbucking arrangement.
While the use of pairs of pick-up assemblies in a humbucking arrangement is effective in eliminating extraneous noise, a new problem is created, that being that the sound produced by a humbucking pick-up assembly is not as sharp and as clear as that obtainable from a single pick-up assembly. The reason for this is felt to be that each pick-up assembly of the humbucking pair interferes with the operation of the other pickp-up assembly of the pair. This is because the coil of each pick-up assembly acts as a load for the coil of the other pick-up assembly and the magnetic field of one pick-up assembly interferes with the magnetic field of the other. Thus, it would be desirable to provide a humbucking pick-up assembly having the tone producing qualities of a single coil but this has been unobtainable heretofore.